It is estimated that 18 million people worldwide suffer from Alzheimer's disease, which is the most common cause of dementia. According to the World Health Organization, of the 35 million people currently living with dementia globally, 58% live in low- and middle-income countries and by 2050 this figure is projected to reach 71% of the total.
The multi-centre UK study, led by Professor Robert Howard at King's College London, is the first trial to demonstrate the value of continued drug intervention for those patients with moderate to severe Alzheimer's disease who have deteriorated beyond the point where donepezil is currently recommended.
The study, to be published in the New England Journal of Medicine
, looked at two drugs: donepezil and memantine. Donepezil is the most commonly prescribed of the dementia drugs and is recommended for patients at the earliest stages of Alzheimer's disease. Doctors are currently advised to stop prescribing donepezil when the disease progresses to become moderate to severe and until now there has been no clear evidence that continuing treatment is of benefit to patients.
Over the course of the trial, patients who continued to take donepezil showed considerably less decline in cognition - memory, orientation, language function - and function (retained ability to carry out simple daily tasks and self-care) than those taking a placebo drug. The benefits seen with continued treatment were clinically important and were greater than those previously seen in patients with less severe Alzheimer's disease. Whilst the effect was slightly smaller, starting memantine treatment also resulted in significantly better cognitive and functional abilities compared with those taking a placebo.
Professor Robert Howard, lead author from the Institute of Psychiatry at King's says: "As patients progress to more severe forms of Alzheimer's disease, clinicians are faced with a difficult decision as to whether to continue or not with dementia drugs and, until now, there has been little evidence to guide that decision. For the first time, we have robust and compelling evidence that treatment with these drugs can continue to help patients at the later, more severe stages of the disease. We observed that patients who continued taking donepezil were better able to remember, understand, communicate and perform daily tasks for at least a year longer than those who stopped taking the drugs. These improvements were noticeable to patients, their caregivers and doctors. Both donepezil and memantine will soon be off patent and available in very cheap generic preparations. These findings will greatly increase the numbers of patients in the developed and developing world that we are able to treat."
Professor Nick Fox, MRC Senior Clinical Fellow at the Institute of Neurology, University College London, says: "The number of people with Alzheimer's disease and other forms of dementia is reaching critical levels. It has never been more important to invest in research which will enable doctors to make informed decisions based on the best evidence possible when deciding what treatments to give patients. The MRC has an ongoing commitment to the development of effective, safe treatments that will improve the quality of life for people with Alzheimer's disease and their care givers."
Professor Clive Ballard, Director of Research at Alzheimer's Society, says: "Thanks to the Alzheimer's drug donepezil, tens of thousands of people in the early to moderate stages of the condition are able to recognise their family for longer, play with their grandchildren and make vital plans for the future. This major new trial now shows that there could also be significant benefits on continuing the treatment into the later stages too. There are 750,000 people with dementia in the UK yet currently prescription levels of Alzheimer's drugs are still low. If this is to change we have to improve the shocking diagnosis rates and ensure everyone is given the opportunity to try treatments."